High blood pressure is defined as a systolic (top number) blood pressure of 140 mmHg or more, or a diastolic (bottom number) blood pressure of 90 mmHg or more. A normal blood pressure is 120/80 mmGh or lower. Some patients with mildly elevated blood pressure can control it with a low-salt diet, high in fruits and vegetables, and low-fat dairy products, (the DASH) diet, exercise and weight loss. The DASH diet also may prevent the development of high blood pressure. Most patients with elevated blood pressure will need medication. The higher your blood pressure, the greater your risk.

One of the major medical advances of the last half-century is the availability of a variety of medications to control blood pressure. In 1945, a month before President Franklin D. Roosevelt's death from a stroke, his blood pressure was 240/180 mmHg. His doctor never told him he had hypertension because he didn't want to worry the President—for there were no medications available to treat high blood pressure at that time. Over the ensuing five decades, as more and more effective antihypertensive medications were developed, the incidence of stroke declined dramatically.

High blood pressure inside the arteries causes "wear and tear" and not only causes stroke, but aneurysms (ballooning out) of the arteries, which can rupture, and kidney failure. Damage to the arteries and the increased heart work that high blood pressure causes, can lead to heart failure.

The incidence of heart failure increases with age and is the most common cause of hospital admission in patients over age 65. The only way you know if your blood pressure is elevated is to measure it, and the only way you can be sure your blood pressure is controlled is to measure it. You can't rely on how you feel—you can feel great and your blood pressure can be severely elevated. That is why high blood pressure is referred to as "the silent killer."